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Concentration of CO2 in the Atmosphere

A Net Zero Concrete Home


Homerun House small

Homerun House, a net-zero concrete demonstration home where the concrete modulates the temperature Cont’d on p.29 and a solar PV array is employed. Photos courtesy of Dave Sellers.

The low cost of longevity

By George Harvey

Tell and environmentalist that you are building a net-zero home out of concrete, and you will very likely elicit a response of “Huh?”

Award-winning Vermont architect Dave Sellers, however, has a story about net-zero buildings and concrete. In the end, if good care goes into the design of a concrete building to ensure that it needs no fossil fuels for comfortable living, justifying the use of concrete may be a simple matter. Believe it or not, this very practical issue may be determined by aesthetics.

Sellers said of this, “It is not just that it be net-zero. That is a dead end. It must also be beautiful.”

From an environmental point of view, the thing that makes concrete attractive is its lasting qualities. It can outlast wood by a factor of eight or ten, because it does not rot or burn. There are concrete buildings still in use that were built in ancient times. The best known is possibly the Pantheon in Rome, which is nearly 1,900 years old. Today, concrete can be much higher quality than what the ancient Romans had, so it could be made to last even longer.

So the carbon footprint associated with construction may be slightly higher than it would be for a similar building of wood, especially compared to other building materials. But that carbon footprint is for a much longer period, if the structure is made of concrete. Concrete can be better than wood, given the overall lifetimes of the buildings.

And this explains the matter of aesthetics. “If you want people to use a building for five hundred years, it has to be beautiful,” Sellers said, “otherwise they will tear it down.”

Sellers’ whole approach to building, and evidently to living, includes the frugal use of materials. It is a matter he has been studying and working with since he got his Masters in Architecture from Yale School of Architecture in 1965.

“A bunch of us got out of grad school at Yale and decided that our education was incomplete,” Sellers said. “We didn’t know how to make anything. We came to Vermont. We had $2000, and we got some land for $1000 down and $1000 per year. For practical purposes, it was free land, free labor, free food, camping out. We made these buildings in a community of like-minded thinkers.”

Over the course of fifty years, Sellers did a lot of experimental building. “We became experts on plywood,” he said. “And then we realized concrete was a better material. We got a lot of forms that were left over from a building with lots of arches, and we reused them. We used the forms to make a concrete building with a lot of arches, and we called it the Archie Bunker. When we were done with the forms, we used them for a class on how to make furniture out of scrap lumber.”

Sellers is now about to open a new building called the Homerun House. Another name for it is HOTFU, a name given it by a French volunteer, engineer Audrey Martinez. HOTFU is an acronym for “house of the future.”

One of Sellers’ principles is that nothing should be wasted. There is no burn pile, nothing goes to a landfill. Wood forms become furniture. There is always a purpose for any extra concrete.

Another is that nothing should be used that can rot. Window forms are made of used blackboard slate instead of wood. Many of the windows were made at the site, with some having as many as five layers of glass. Large windows were made of Plexiglass for safety. Windows that were purchased came from three different manufacturers, and one was made with a single thickness of glass, so they could be compared as an experiment.

Homerun House has no interior walls, because they are not necessary. The floor is special. Aside from the fact that it has covered troughs in it for plumbing and electric circuits, it has a false floor over three feet of soil in an atrium section of the living area so plants can be planted in it. Currently, they are planned to include citrus trees, bananas, and pineapple.

The house has passive solar heat, of course. The concrete modulates the temperature. Where necessary, there is spray foam insulation on the walls and ceiling rated at R-40 to R-55. A concrete house is easy to air-seal, but care has to be given to ventilation; there is a wall in this house that is fourteen feet long that will tilt in or out for fresh air. There is also a fireplace, but not to heat the house. It is there for people to gather around when they return from skiing.

Homerun House will be a demonstration house, and so will be given to the Madsonian Museum of Industrial Design. It is being opened to the public, possibly as soon as November.

Sellers has an interesting view of a possible future. He pointed out that if houses were built so they would be long-lasting and beautiful, we could come to what he called a “Third Golden Age.” Someday, he said, “You could walk down any street in the world, and it would be lined with beautiful buildings.” Just imagine how different the world can be.

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